Inks that can be used to write on glass surfaces are known, examples of which include, besides so-called oil-based inks: inks containing glycol ether or other organic solvent, pigment, 25° C. water, as well as resin whose solubility in ethanol is 7% or less such as vinyl chloride/vinyl acetate copolymer, ester acrylate polymer, or other acrylic resin as described in Patent Literature 1; glass marking inks for showing the presence of glass containing colorant, at least one type of styrene/ester (meth)acrylate copolymer emulsions, ester (meth)acrylate/vinyl acetate copolymer emulsions, ester (meth)acrylate/vinylidene chloride copolymer emulsions, and other resin emulsions and alkali-soluble resins, as well as water-soluble resin, thixotropic agent, and water as described in Patent Literature 2; and water-based pigment inks for glass containing pigment, ester poly(meth)acrylate, or other resin emulsion as described in Patent Literature 3.
Furthermore, Patent Literature 4 describes a water-based ink composition for writing instruments that can be used to write not on glass surfaces, but on non-penetrated surfaces, characterized in that such composition contains at least pigment, water, and polycarbonate/polyol copolymer urethane emulsion.
These water-based inks can certainly be used to write on glass and ceramic surfaces, but due to the hydrophilicity of glass and ceramic surfaces, the water in such water-based ink, which serves as the medium, tends to exist between such hydropholic surface and the organic resin or colorant of water-based ink. This prevents writing from being fixed on glass or ceramic surfaces sufficiently, meaning that these inks, lacking in water resistance, hot water resistance, and scratch resistance, cannot be set on glass and ceramic surfaces.
Accordingly, when glass products, etc., bearing writing made with such water-based inks are washed, such writing is washed off.